An engagement session is often a couple's first time being photographed together in this way, so put the direction on the photographer, not the couple, to figure out.
Location choice sets the tone for the whole session, and it's worth confirming with the couple in advance rather than deciding on arrival — a location that means something to them usually photographs with more genuine emotion than a generic scenic spot. Timing around golden hour, where the schedule allows, gives flattering light without needing much additional gear.
Most couples aren't used to being photographed and will default to stiff, camera-aware poses unless actively directed — having a handful of movement-based prompts (walking, a quiet conversation, a genuine laugh) ready in advance produces far more natural results than static posing alone. Coordinating wardrobe between the two people, so neither outfit visually competes with the other, is worth a quick conversation before the day.
None of this needs to be rigid — the point of preparing location, timing and posing direction in advance is so the couple can relax into the session instead of feeling like they're being tested.
A few things to plan for